1. Field of the Invention
This invention relates to a clear, therapeutic hair care composition having low pH for use in local treatment of dandruff, seborrheic dermatitis, and psoriasis of the scalp which resists decoloration due to oxidative decomposition.
This invention further relates a clear, therapeutic hair care composition having low pH for use in local treatment of dandruff, seborrheic dermatitis, and psoriasis of the scalp which contains a detergent shampoo base, a therapeutic amount of keratolytic agents and keratolytic stabilizing agents in an amount sufficient to stabilize the keratolytic agents against decoloration decomposition from oxidation.
This invention further relates to a method to create a clear, therapeutic hair care composition having low pH which resists decomposition due to oxidation.
Other objects of this invention become apparent to those ordinarily skilled in the art from the reading of the description of the preferred embodiment.
2. Description of the Prior Art
Salicylic acid for use as a keratolytic agent in hair care compositions for the local treatment of dandruff, seborrheic dermatitis, and psoriasis of the scalp is old and well known in the art. However, use of salicylic acid as a keratolytic agent in shampoos designed for use in the local treatment of dandruff, seborrheic dermatitis, and psoriasis of the scalp entails certain drawbacks. Among these are decomposition of the keratolytic agent, namely the salicylic acid, by ultraviolet radiation induced oxidative decomposition. The decomposition causes the shampoo to change colors which is not at all desirable for a shampoo. Accordingly, all such products are packaged in opaque containers such that the effects of ultraviolet radiation-catalyzed oxidative decomposition are diminished if not completely removed. The shampoo is protected from exposure to ultraviolet radiation by the container itself and the shampoo, being opaque in color, masks the decomposition of the salicylic acid, which is the keratolytic agent, and so the consumer never really is aware whether or not the shampoo is effective in the local treatment of the nonexudative seborrheas of the scalp condition which prompted him to buy and use the product in the first place.
The use of a stabilizing agent for the keratolytic agent is also a desirable and well known accomplishment of the prior art. Many such stabilizing agents have been proposed such as those entailed in Petrow et al. U.S. Pat. No. 4,295,985. Petrow et al. discloses the use of alkali metal thiosulfates in shampoos which act as reducers in the composition and would be candidates for stabilizers of the keratolytic agent, namely salicylic acid.
Tertiary amines are also generally susceptible to oxidation by mild oxidating agents and would serve as chelating agents to prevent the reduction of the salicylic acid. U.S. Pat. No. 2,697,118 describes N,N,N',N'-tetrakis (2-hydroxyproply) ethylenediamine, the crosslinking agent and catylist in rigid type polyurethane foams. This compound was found to form stable metal ion complexes with such cationic ions AjI, PbII, HgII, CuII, cadmium, cobolt, nickel and zinc. However, none of the prior art, insofar as we are able to determine, has recognized the use of tertiary amines as chelating agents or reducing agents to stabilize salicylic acid and other siliciates in a shampoo composition for use in the local treatment of dandruff, seborrheic dermatitis, and psoriasis of the scalp. Moreover, it has been found, that by use of the tertiary amines, it is possible to form a stable clear hair care composition having a low pH for use in the local treatment of dandruff, seborrheic dermatitis, and psoriasis of the scalp which resists decomposition, i.e. discoloration catalyzed by ultraviolet radiation exposure. It has been found that by the use of the tertiary amines in conjunction with other salicylic acids tabilizers, the production of a clear anti-dandruff shampoo is now possible which hereto before had been an impossibility.